The most common childhood leukaemia can be “cured” in mice with the flick of a genetic switch, Australian researchers have discovered.

Mice at Melbourne’s Walter and Eliza Hall Institute developed a type of leukaemia, B-ALL, after having the “tumour suppressor” gene Pax5 deactivated. But when scientists switched the gene back on, they found the cancerous cells were “coaxed” back to their normal state.

“The cells regain their identity,” a lead scientist on the study, Grace Liu, said. “[The cancer] disappears from the blood, the bone marrow and all the areas where the leukaemia normally develops.”

The findings were published this week in the journal Genes & Development.

One-third of children with leukaemia are found to lack healthy levels of Pax5.

When the gene is damaged or only partially present, developing white blood cells can become trapped in an immature state and turn cancerous.

The study is an example of differentiation therapy, an approach to cancer treatment that seeks to rehabilitate cells that have become malignant. Chemotherapy, by contrast, “just blasts the [cancerous] cells and causes them to die”, Liu said.

Liu said it was “intriguing” that simply restoring Pax5 was enough to turn B-ALL cells to normal, as the gene is just one of many that are usually mutated in leukaemia.

But Dr Ross Dickins, another scientist on the study, said it would be difficult to develop drugs to restore the Pax5 gene, or the “about 100” other genes known to suppress tumours.

“However, by understanding the mechanisms by which Pax5 loss causes leukaemia we can begin to look at ways of developing drugs that could have the same effect as restoring Pax5 function,” he said.